The invention pertains to a method for manufacturing a dental restoration for at least one section of a dental arch on the basis of digital overall data, which is calculated in relation to individual data, that is based on three-dimensional optical individual measurements performed on an intra-oral basis of an area containing at least one section of the dental arch, whereby at least one area of the dental arch is measured together with a reference which supplies three-dimensional information, and the overall data are calculated from the individual data while considering the reference.
In order to produce dentures, it is known to produce a duplicate from one area of the dental arch where a dental restoration is to be introduced. Single scans are then produced from sections of the duplicate, which are then spatially positioned with respect to one another, in order to calculate the digital data. The respective data are then used in coordination with configurations of the restoration, which have been recorded in a library, in a CAD/CAM process to perform the restoration by means of processing, such as grinding of a blank preferably comprised of ceramic.
In order to minimize errors when calculating the data that are necessary for the manufacturing of the dental restoration, which are related to measurements, it is known from WO-A-2005/058183 how to physically assign the measured individual duplicate sections based on a reference.
DE-B-10 2004 051 165 also uses a scannable model as the basis for manufacturing the dentures, whereby scanned segments of the model are spatially positioned with respect to one another by means of a reference.
US-A-2003/0219148 provides a method for the generation of a three-dimensional model of a dental arch on the basis of digital data which are determined in relation to given individual data, which in turn have been produced by three-dimensional optical individual measurements. In order to be able to combine overlapping individual measurements by means of stitching, three-dimensional references are also scanned, which can cover areas that are to be partially scanned.
The object of EP-A-1 710 536 is a method for the three-dimensional shape capture particularly of a dental model. Areas of the model are optically measured together with a reference model, whereby corrective values are determined from the deviation between the actual and real values of the reference object.
In a method for determining the shape of a duplicate of a remaining dental area according to WO-A-2005/058183 that is to be provided with a dental restoration, duplicate sections are referenced in a spatial relationship to one another based on a reference, which is recorded in a computer.
A standard scale for use with a photogrammetric measuring device has been described in DE-A-197 49 107.
U.S. Pat. No. 7,065,243 reveals a method for producing a dental model. It determines an intra-oral measuring of one or several teeth with a concurrent presence of a reference for the position of a camera, which measures the tooth or teeth. With the camera position being a known fact in respect to the tooth or teeth, a 3-D-model is thus produced, which is then necessary to produce the denture. A corresponding method is burdensome and also shows the disadvantage that the reference, which is shaped as a square open box, shades the tooth or teeth.
The intra-oral measurement of at least one section of the dental arch is performed from different angles while the distance to the camera varies. The individual images are then combined through stitching and merging to develop three-dimensional data of the dental arch section, in order to be able to produce the desired denture based on the digitally available data. It is in this case possible that accumulations of small deviations may cause distortions of the 3-D-data set which exceed the acceptable tolerance levels.